FILE - In this Thursday, Sept. 13, 2012 file photo, bloodstains at the main gate believed to be from one of the American staff members of the U.S. Consulate, after an attack that killed four Americans, including Ambassador Chris Stevens on the night of Tuesday, Sept. 11, 2012, in Benghazi, Libya. Britain's Foreign Office urged U.K. nationals to immediately leave the eastern Libyan city of Benghazi in response to an imminent threat against Westerners. Arabic writing reads, " Villa of Jamal al Beshary". which was written by the original owner to protect the property from another attack. (AP Photo/Mohammad Hannon, File)